Modulaattori

Modulaattori, or modulator in English, is a device or circuit that applies a modulating signal to a carrier signal in order to convey information. Modulation is essential for transmitting data over physical channels, shaping bandwidth, improving signal-to-noise ratio, and enabling multiplexing of multiple signals on a single medium.

There are several classes of modulators. Analog modulation includes amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). Digital modulation schemes such as amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK), and quadrature amplitude modulation (QAM) encode binary data into variations of the carrier. In optical communications, modulators adjust light intensity, phase, or polarization via electro-optic or acousto-optic effects. Modern systems often combine multiple modulation methods and use pulse shaping and digital processing to optimize performance.

How a modulaattori works can vary by implementation. A typical radio-frequency modulator combines a carrier source (an oscillator), a modulating input (the information signal), and a modulation element (such as a mixer or multiplier), sometimes followed by filters and amplifiers. In digital and optical systems, modulation may be implemented in software or programmable hardware with precise timing and waveform control.

Applications of modulaattori span radio broadcasting, television RF links, mobile and satellite communications, radar, data links, and fiber-optic networks. The choice of modulation scheme depends on channel characteristics, required data rate, and resilience to noise and interference.